Improved machine for stretching leather



UNITED STATES PATENT OFFICE.'

JOHN H. HASKELL, OF BALTIMORE, MARYLAND.

IMPROVED MACHINE FOR STRETCHING LEATHER.

T0 all whom it may concern:

Be it known that I, JOHN H. HAsKELL, of Baltimore, in the county of Baltimore and State of Maryland, have invented a new and useful improvement in Machines for Stretching Leather; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, in which- Figure l is a vertical longitudinal section of a machine constructed after the plan of my invention, and Fig. 2 an end view; and Figs. 3, 4, 5, 6, and 7 views of detached portions of the machine.

'Similar letters of reference in each of the several figures indicate corresponding parts.

The nature of my invention consists, iirst, in making each of the gripping devices of two or more separate cams Z.

It consists, second, in arranging the camsl upon an adjustable bar m in such a manner that not only the whole gripping surface can be adjusted for pieces of leather of various thickness, but that each cam Z can also adjust itself'to the varying thickness of one piece of leather.

It consists, third, in combining a grippingcam constructed of separate cams Zand of an adjustable bar m with a lever a, pivoted to the main frame of the machine at (l.

It consists, fourth, in the combination of a iianged pawl fu and a sliding cam in the manner and for the purposes hereinafter to be described.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

A lever a, the forward part of which is provided with ratchet-teeth c, is pivoted at d to the uprights u of the main frame of the machine. A curved table b is fastened to the rear part of the lever a. A frame g g is made to slide upon the front part of the lever a. Two vertical brackets h extend from this frame, each bracket being provided with an opening, the bottom part k of which is an arc of a circle. A small sliding block fi iits in the upper end of said opening. A bar m is placed across the machine, its ends reaching through the openings in both the brackets.

The lower edge of the bar rests upon the bottom part 7e of the openings, While the upper edge of the bar fits` into an indentation in each of the two sliding blocks 'a'. By moving the lower edge of the bar along the arc kthis edge can be raised more or less from the upper surface of the frame g and the bar be confined in the desired position by tightening the set-screws j, against which the sliding blocks bear. A number of hollow cams Zare slipped over said bar m. The bottom part of the hole in each cam is of a width equal to the thickness of the bar m, while the upper part of the hole is wider and arched so as to allow each cam to swing Yupon the bar. The foot of each of these cams is serrated and is thicker at the outer end p than at the inner end o. It will be seen that the serrated surface at p will be made to approach the sern rated upper surface of g', and therefore the open space between the two surfaces will be diminished when the cam Z swings forward, and vice versa. A similar bar m, cams Z, and brackets h are arranged upon a frame g, fastened to the uprights n of the main frame immediately in rear of the pivot d. The piece of leather f to be stretched is placed over the table b and its ends confined between the serrated surfaces of the camsland of the frames g and g. The lower edges of the bars m are moved along the curved bottoms of the openings in the brackets until the leather is held tight between the serrated surfaces of the cams and frames, and the bars m m are confined in these positions by tightening the screws j. The forward end of lever a, which is suspended by a cord lr tied to the frame g at q and passing over a pulley s, attached to one of the rafters t of the ceiling, is now allowed to descend by its own weight, so as to stretch the leather f across the curved surface of the table b. As the leatherbegins to be stretched the pawl fu, pivoted to frame g', as will hereinafter be described, takes into one of the ratchet-teeth c and prevents the frame g from being drawn backward. As the tension of the leather and its tendency to slip from between the serrated surfaces increases the grip of the cams increases in the same ratio as the tension of the leather causes the cams to swing upon the bars m, so as to approach the thicker portions p of the cams to the serrated surfaces of the frames g g',

thereby decreasing the space between which the ends of the leather are confined. Each cam can accommodate itself to the thickness of the leather, however unequal it may be in one piece of leather, and thus vno portion of the ends of the leather can escape from the grip of the cams.

The pawl QJ has two flanges which fit loosely over a projection y, extending from frame g. The upper flange is pivoted to the projection 'y at w, the pivot-hole in the flange being somewhat larger than the pivot, so as to allow the end of the pawl to be lifted from out of the ratchet-teeth c. This is done by a cam projection upon the forked end x of a rod .e being drawn forward, so that the cam :r pushes the lower fiange of pawl 'u out, and thus lifts the end of the pawl. The forked end of the rod z slides over the projection y, and its outer end is provided with a slot w', playing over a pin o'. A knob y at the outer end of rod z serves to operate the rod. It will be understood that the pawl will remain in its raised position until the rod z is again pushed back, so as to release the lower flange of the pawl from the cam By this means the pawl can be kept suspended until the piece of leather has been properly arranged. As soon as it is readyto be stretched the rod z is pushed back and the pawl'takes into the rathe-t'c. Y

What l claim as my invention, and desire to secure by Letters Patent, is

1. Making each of the gripping devices of two or more separate cams Z, substantially as and for the purposes set forth.

2. Arranging the cams l upon an adjustable bar m in such a manner that not only the whole grippingsurface can be adjusted for pieces of leather of various thicknesses, but that each cam Z can also adjust itself to the varying thickness of one piece of leather, substantially as set forth.

3. Combining a gripping-cam constructed of separate cams Z and of an adjustable bar m with a lever a, pivoted to the mainframe of the Vmachine at d, substantially as and for the purposes set forth.

4. The combination of a flan ged pawl o and a sliding cam 0c, substantially as and for the purposes set forth.

The above specification of my improvement. in machines for stretching leather signed by me this 21st day. of lWIarch, 1860.

JOHN H. HASKELL.

Witnesses:

GOODWIN Y. ATLEE, R. YV. FENWICK. 

